From f7079bf876975dd26f7c461f6d89bcec8bc8c70a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=89milie=20Feral?= <emilie.feral@numworks.com>
Date: Tue, 29 Nov 2016 16:23:05 +0100
Subject: [PATCH] [apps/graph/graph] Handle the cursor moves in the graph view

Change-Id: I5db563e4b88a6dd33dd6fc9ce5a4cf1337d43c31
---
 apps/graph/graph/graph_controller.cpp | 22 ++++++++--
 apps/graph/graph/graph_view.cpp       | 63 ++++++++++++++++++++++++++-
 apps/graph/graph/graph_view.h         |  6 ++-
 3 files changed, 84 insertions(+), 7 deletions(-)

diff --git a/apps/graph/graph/graph_controller.cpp b/apps/graph/graph/graph_controller.cpp
index de1b39db3..97fdce53c 100644
--- a/apps/graph/graph/graph_controller.cpp
+++ b/apps/graph/graph/graph_controller.cpp
@@ -150,13 +150,27 @@ bool GraphController::handleEvent(Ion::Events::Event event) {
       m_view.reload();
       return true;
     }
-    if (event == Ion::Events::OK) {
-      m_view.moveCursorRight();
+    if (event == Ion::Events::Left) {
+      m_view.moveCursorHorizontally(-2);
+      return true;
+    }
+    if (event == Ion::Events::Right) {
+      m_view.moveCursorHorizontally(2);
       return true;
     }
     if (event == Ion::Events::Up) {
-      headerViewController()->setSelectedButton(0);
-      m_headerSelected = true;
+      Function * f = m_view.moveCursorUp();
+      if (f == nullptr) {
+        headerViewController()->setSelectedButton(0);
+        m_headerSelected = true;
+      }
+      return true;
+    }
+    if (event == Ion::Events::Down) {
+      Function * f = m_view.moveCursorDown();
+      if (f == nullptr) {
+        return false;
+      }
       return true;
     }
     return false;
diff --git a/apps/graph/graph/graph_view.cpp b/apps/graph/graph/graph_view.cpp
index 371bb079e..9f326ca2f 100644
--- a/apps/graph/graph/graph_view.cpp
+++ b/apps/graph/graph/graph_view.cpp
@@ -2,6 +2,7 @@
 #include "../../constant.h"
 #include <assert.h>
 #include <math.h>
+#include <float.h>
 
 namespace Graph {
 
@@ -59,6 +60,7 @@ Context * GraphView::context() const {
 
 void GraphView::reload() {
   markRectAsDirty(bounds());
+  initCursorPosition();
   layoutSubviews();
 }
 
@@ -76,12 +78,69 @@ int GraphView::numberOfYLabels() const {
   return ceilf((max(Axis::Vertical) - min(Axis::Vertical))/(2*m_axisInterval->yScale()));
 }
 
-void GraphView::moveCursorRight() {
-  KDPoint offset = KDPoint(2,0);
+void GraphView::initCursorPosition() {
+  float center = (min(Axis::Horizontal)+max(Axis::Horizontal))/2.0f;
+  m_indexFunctionSelectedByCursor = 0;
+  Function * firstFunction = m_functionStore->activeFunctionAtIndex(0);
+  float fCenter = firstFunction->evaluateAtAbscissa(center, m_evaluateContext);
+  m_cursorPosition = KDPoint(160, floatToPixel(Axis::Vertical, fCenter));
+}
+
+void GraphView::moveCursorHorizontally(KDCoordinate xOffset) {
+  KDPoint offset = KDPoint(xOffset,0);
   m_cursorPosition = m_cursorPosition.translatedBy(offset);
+  Function * f = m_functionStore->activeFunctionAtIndex(m_indexFunctionSelectedByCursor);
+  float ordinate = f->evaluateAtAbscissa(pixelToFloat(Axis::Horizontal, m_cursorPosition.x()), m_evaluateContext);
+  m_cursorPosition = KDPoint(m_cursorPosition.x(), floatToPixel(Axis::Vertical, ordinate));
   layoutSubviews();
 }
 
+Function * GraphView::moveCursorUp() {
+  float x = pixelToFloat(Axis::Horizontal, m_cursorPosition.x());
+  Function * actualFunction = m_functionStore->activeFunctionAtIndex(m_indexFunctionSelectedByCursor);
+  float y = actualFunction->evaluateAtAbscissa(x, m_evaluateContext);
+  Function * nextFunction = actualFunction;
+  float nextY = FLT_MAX;
+  for (int i = 0; i < m_functionStore->numberOfActiveFunctions(); i++) {
+    Function * f = m_functionStore->activeFunctionAtIndex(i);
+    float newY = f->evaluateAtAbscissa(x, m_evaluateContext);
+    if (newY > y && newY < nextY) {
+      m_indexFunctionSelectedByCursor = i;
+      nextY = newY;
+      nextFunction = f;
+    }
+  }
+  if (nextFunction == actualFunction) {
+    return nullptr;
+  }
+  m_cursorPosition = KDPoint(m_cursorPosition.x(), floatToPixel(Axis::Vertical, nextY));
+  layoutSubviews();
+  return nextFunction;
+}
+
+Function * GraphView::moveCursorDown() {
+  float x = pixelToFloat(Axis::Horizontal, m_cursorPosition.x());
+  Function * actualFunction = m_functionStore->activeFunctionAtIndex(m_indexFunctionSelectedByCursor);
+  float y = actualFunction->evaluateAtAbscissa(x, m_evaluateContext);
+  Function * nextFunction = actualFunction;
+  float nextY = -FLT_MAX;
+  for (int i = 0; i < m_functionStore->numberOfActiveFunctions(); i++) {
+    Function * f = m_functionStore->activeFunctionAtIndex(i);
+    float newY = f->evaluateAtAbscissa(x, m_evaluateContext);
+    if (newY < y && newY > nextY) {
+      m_indexFunctionSelectedByCursor = i;
+      nextY = newY;
+      nextFunction = f;
+    }
+  }
+  if (nextFunction == actualFunction) {
+    return nullptr;
+  }
+  m_cursorPosition = KDPoint(m_cursorPosition.x(), floatToPixel(Axis::Vertical, nextY));
+  layoutSubviews();
+  return nextFunction;
+}
+
 void GraphView::layoutSubviews() {
   KDRect cursorFrame(m_cursorPosition, 10, 10);
   m_cursorView.setFrame(cursorFrame);
diff --git a/apps/graph/graph/graph_view.h b/apps/graph/graph/graph_view.h
index 106845e26..d833a04b3 100644
--- a/apps/graph/graph/graph_view.h
+++ b/apps/graph/graph/graph_view.h
@@ -30,7 +30,10 @@ public:
 #endif
 
 //  void drawRect(KDRect rect) const override;
-  void moveCursorRight();
+  void initCursorPosition();
+  void moveCursorHorizontally(KDCoordinate xOffset);
+  Function * moveCursorUp();
+  Function * moveCursorDown();
   void setContext(Context * evaluateContext);
   Context * context() const;
   void reload();
@@ -79,6 +82,7 @@ private:
 
   CursorView m_cursorView;
   KDPoint m_cursorPosition;
+  int m_indexFunctionSelectedByCursor;
   constexpr static KDCoordinate k_labelWidth =  32;
   constexpr static KDCoordinate k_labelHeight =  12;
   constexpr static KDCoordinate k_labelMargin =  4;